Contact assembly of circuit interrupter



Oct. 6, 1970 TUT OMU HANAFUSA ET AL 3,533,027

CONTACT ASSEMBLY OF CIRCUIT INTERRUPTER Filed Dec. 18, 1968 2 Sheets-Sheet 1 INVENTOR TUTOMU HANAFUSA YOSHIO KOBAYASHI ATTORNEYS 1970 TUTOMU HANAFUSA ET AL CONTACT ASSEMBLY OF CIRCUIT INTERRUPTER 2 Sheets-Sheet 2 FiledDec. 18, 1968 INVENTORS TUTOMU HANAFUSA YOSH IO KOBAYASHI v F|G.5

BY 5M ATTORNEYS United States Patent "ice 3,533,027 CONTACT ASSEMBLY OF CIRCUIT INTERRUPTER Tutomu Hanafusa, Osaka, and Yoshio Kobayashi, Nara,

Japan, assignors to Terasaki Denki Sangyo Kabushiki Kaisha, Osaka, Japan Filed Dec. 18, 1968, Ser. No. 784,799 Claims priority, application Japan, Dec. 29, 1967, 43/110,615 Int. Cl. H01h 77/10 US. Cl. 335195 4 Claims ABSTRACT OF THE DISCLOSURE In the closed position of a circuit interrupter, two stationary contact arms are bridged by and disposed in parallel to two movable contact units each including two juxtaposed movable arms with each pair of aligned movable contacts engaging the opposite stationary contact. Each unit is pivoted on a pin fixed to a holder and maintained in rolling contact with the other unit. An anchoring pin loosely extends through each unit and tension springs are spanned between the pins to cooperate with each pin to impart to each pair of aligned movable contacts substantially equal contact pressures. The movable arms respond to an electromagnetic repulsion generated between the movable and stationary arms due to the ocurrence of a shortcircuiting current to be rotated away from the stationary arms. The anchoring pins move along bilateral notches on the holder to limit rotation of the movable arms.

This invention relates to improvements in a movable oontact assembly of a circuit interrupter disposed in substantially parallel relationship with respect to the opposite stationary contact assembly in the closed position of the interrupter and responsive to an electromagnetic repulsion generated between both the contact assemblies due to a fiow of very excessive current such as shortcircuiting current through the interrupter to complete an interruption of the current within a short period of time while limiting the magnitude of the current.

An object of the invention is to provide a new and improved movable contact assembly of the type as above described including a pair of movable contact arms of the same configuration disposed in juxtaposed parallel relationship and having the respective movable contacts normally engaging the opposite stationary contact under substantially equal contact pressures.

The invention accomplishes this object by the provision of a circuit interrupter comprising, in combination, a stationary contact assembly having attached to one end a stationary contact, a movable contact assembly including a pair of identical movable contact arms, disposed in juxtaposed parallel relationship and having attached to one end the respective movable contacts, the stationary and movable contact assemblies being disposed in substantially parallel relationship in the closed position of the interrupter, holder means, a support pin fixed to the holder means to pivotably support the other end portions of the movable contact arms, an anchoring pin loosely extending through the intermediate portions of the movable contact arms, tension spring means anchored at one end to the anchoring pin to cooperate with the latter to impart to the pair of movable contacts substantially equal contact pressures under Patented Oct. 6, 1970 which they are maintained in contact with the stationary contact in the closed position of the interrupter, the movable contact arms being responsive to an electromagnetic repulsion generated between the movable and stationary contact assemblies due to a flow of very excessive cur rent through the interrupter to be rotated away from the stationary contact assembly thereby to interrupt the current, and means for limiting the rotational movement of the movable contact arms.

The last-mentioned limiting means may be preferably a guide notch disposed on the holder means along which the anchoring pin is movable during the rotational movement of the movable contact arms.

The invention will become more readily apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a side elevational view, partly in section of a circuit interrupter constructed in accordance with the principles of the invention;

FIG. 2 is a fragmental perspective view of a movable contact assembly shown in FIG. 1;

FIG. 3 is a side elevational view, partly in section of one portion of the movable contact assembly shown in FIGS. 1 and 2;

FIG. 4 is a fragmental side elevational view of a modification of the invention; and

FIG. 5 is a fragmental plan view of the device shown in FIG. 4.

While the invention will be described in conjunction with a circuit interrupter of three pole type, it is to be understood that the same is equally applicable to circuit interrupters having any desired number of poles. Also it is to be understood that the component common to all the poles will be described in terms of the central pole alone.

Referring now to the drawings and in particular to FIG. 1, there is illustrated a three pole circuit interrupter constructed in accordance with the principles of the invention. An arrangement illustrated comprises a closed enclosure including a main body member 1, a detachable top cover member 2 and a detachable bottom cover member 3. All the members 1, 2 and 3 may be conveniently made of any suitable electrically insulating plastic by the molding technique.

Horizontally disposed within the main enclosure body 1 is a stationary contact assembly generally designated by the reference numeral 4 including a pair of bilaterally symmetric stationary contact arms 5s and I each having an L-shape. The contact arms 5s and l are provided at one end with a pair of stationary contacts 6s and 1 respectively and the other end of the contact arm SS is connected through an electrical conductor 7 to a source terminal 8s disposed on one side of the main enclosure body 1 while the other end of the contact arm 5! is connected to a load terminal 8l is disposed on the opposite side of the main body in the manner as will be described hereinafter.

A movable contact assembly generally designated by the reference numeral 9 is disposed on opposite relationship -with respect to the stationary contact assembly 4 within the main body 1 and includes a pair of bilaterally symmetric movable contact units 10s and I each divided into a pair of identical movable contact arms 10sa and sb or 101a and lb disposed in juxtaposed parallel relationship and provided at one end with the respective movable contacts Ilsa, sb, la and lb. Each pair of juxtaposed contact arms 10m and ab or la and lb are pivotably mounted adjacent the other ends on a support pin 12s or I fixed to a pair of holding plates 13 and 13 therebetween and always maintained in engagement with the longitudinally aligned contact arms by having their other end portions in the form of circular arcs having their centers lying on the axes of the pins 12s and l and contacting each other.

In the closed position of the interrupter the two movable contact arms 10m and sb or 10la and lb are disposed in substantially parallel relationship with respect to the directly opposite stationary contact arm s or 5l with the juxtaposed movable contacts 11sa and sb or 111a and lb maintained in contact with the opposite stationary contact 6s or I.

As best shown in FIG. 2, an. anchoring pin 14s or 141 loosely extends through the intermediate portions of the juxtaposed contact arms sa and sb or 101a and lb and is slidable along aligned guide notch 15s or 1'5l disposed on either of the vertical sides of the holder plates 13 on the lower portions. A pair of parallel tension springs 16a and b are spanned between the anchoring pins 14s and I through the respective anchoring pieces 17s and l fixed 0n the pins and on. either side of the movable contact assembly 9 for the purpose of imparting to the movable contacts contact pressures under which they engage the opposite stationary contacts and of imparting to the movable contact arms contact pressures under which the above-mentioned arcuated end portions thereof are maintained in contact relationship.

For the purpose as will be apparent hereinafter, a pair of balance rods 18s and l are disposed on either side of the movable contact assembly 9 and have one end pivotably mounted on the anchoring pins 14s and l respectively and the other ends pivotably mounted together on a common balance pin 19 which is, in turn, slidable along a pair of aligned slots 20 vertically disposed on the lower end portions of the holding plates 13. Preferably the pin 19 may be provided at both ends with a pair of rollers 21 and 21 adapted to be slidable along a pair of aligned grooves (not shown) disposed on the opposite internal side wall surfaces of the bottom cover number 3. A pair of stoppers 22 are disposed on the internal bottom wall surface of the cover member 3 directly below the rollers 21 to define the lowermost position of the balance pin 19.

As shown in FIG. 1, one flexible shunt lead 23 connects each of the movable contact arms 10sa or sb to the aligned one of the other arms 101a or lb and the bottom cover member 3 defines a pair of opposed are extinguishing compartments 24s and l of the conventional construction around the stationary and movable contact assemblies 4 and 9 respectively. Thus the cover member 3 also serves as a common cover member for the arc extinguishing compartments.

In order to manually open and close the circuit interrupter, that is to say to manually move the movable contact assembly 9 away from and toward the stationary contact assembly 4, there is a switching mechanism generally designated by the reference numeral 25. The switching mechanism comprises a pivotable operating handle 26, a switching lever 27, a tension spring 28, a pair of toggle elements 29, 29 and a contact lever 30'. The contact lever 30 has extending through one end thereof an interlocking switching shaft 31 common to the three poles, and operatively connected to the other end a pair of holder plates 13 as previously described. The switching shaft 31 is operatively connected to both a pair of contact levers and two pairs of spaced holder plates for the remaining two poles although such levers and plates are not illustrated.

For a tripping operation, there is provided a trip mechanism generally designated by the reference numeral 32. The trip mechanism 32 comprises a trip lever 33 pivotably mounted at one end on a pivot pin 34 and operatively connected to the contact lever 30 through the pair of toggle elements 29. The trip lever 33 is normally 4 engaged at the other end by a main trip hook 35 which is, in turn, normally engaged at that end remote from the trip lever 33 by an auxiliary trip hook 36. The auxiliary trip hook 36 normally engages a pawl 37 embedded in a trip shaft 38.

As shown in FIG. 1, an electrically insulating casing 39 accommodates one portion of the trip mechanism 32 and a thermally and electromagnetically responsive mechanism generally designated by the reference numeral 40. The latter mechanism 40 includes an instantaneously tripping electromagnet device 41, and instantaneously tripping rod 42, a trip adjusting screw 43 and a bimetallic element 44.

The stationary contact arm 5l is connected to an electrical conductor 45 which is connected to another electrical conductor 46. The conductor 46 is operatively coupled to both the electromagnet device 41 and the bimetallic element 44 and connected to an intermediate terminal 47 connected to the load terminal 81.

The mechanisms 25, 32 and 40 may be of the conventional design and do not form part of the invention.

The circuit interrupter thus far described is operated as follows: In FIG. 1 wherein the interrupter is illustrated in its closed position, the operating handle 26 can be manually turned to the OFF side to cause the toggle elements 29 to collapse thereby to rotate the contact lever 30 in the clockwise direction as viewed in FIG. .1. This rotational movement of the contact lever 30 is accompanied by the downward movement of the holder plates 13 to permit the movable contacts 11 to be separated from the stationary contacts 6 with the result that the interrupter is put in its open position. It will be appreciated that the guide rollers 21 on the pin 19 having pivotably mounted thereon the balance rods 18s and I slide downwardly along the associated guide grooves (not shown) on the opposite insulating side walls of the arc extinguish compartments 24s and I.

If it is desired to close the opened interrupter, the operating handle 26 can be manually turned to the ON side to cause the process reversed from that as above described to proceed until the movable contacts Ilsa, sb and la, lb are put and maintained in engagement with the stationary contacts 6s and l respectively.

With an ordinary overload current flowing through the circuit interrupter in its closed position, the bimetallic element 44 is heated to deflect. The deflection of the element 44 causes the adjusting screw 43 to rotate the trip shaft 38 in the clockwise direction as viewed in FIG. 1 whereby the pawl 37 disengages from the auxiliary trip hook 36. This is accompanied by the rotational movement of both the hooks 36 and 35 in the clockwise direction as viewed in FIG. 1. Then the hook 35 disengages from the trip lever 33 to permit the toggle elements 29 to collapse. Then the holder plates 13 as maintained in their closed position are depressed along with the movable contact arms 10sa, sb, la and lb to interrupt the associated circuit.

If an excessive current whose magnitude is equal to from five to ten times the rating current for the interrupter flows through the latter in its closed position the electromagnet device 41 is immediately operated to cause the tripping rod 42 to rotate the trip shaft 38 whereby the tripping operation as above described is performed.

If a very excessive current such as a shortcircuiting current flows through the interrupter in its closed position, the current flows in the opposite directions through the stationary and movable contact arms 5 and 10 to develop an electromagnetic repulsion therebetween. While the holder plates 13 are maintained in their closed or original position this electromagnetic repulsion functions to rotate the movable contact arms 10sa and sb on the source side and those 10la and lb on the load side in the counterclockwise and clockwise directions about the axes of the support pins 12s and 1 respectively against the action of the tension springs 16a and b until the movposed on the lower end portions of the holder plates 13 until they reach the lowermost ends of the notches. At the time the movable contact arms are stopped to be rotated. Also the anchoring pins 14s and l are downwardly moved to permit the tension springs 16a and b to pass over the dead points thereof to be reversed in direction of their action. Therefore the rotated contact arms are maintained separated away from the associated stationary contacts resulting in an interruption of the shortcircuiting current.

A little after the interruption operation as above described has been completed, the trip mechanism 32 is operated to release the switching mechanism 25 from its constrained state after which the rollers 21 on the balance pin 19 is downwardly moved along the associated guide grooves on the internal wall surface of the cover member 3 until the movable contact arms are brought into and maintained in their open position.

. It is recalled that the anchoring pins 14s and l loosely extend through the respective juxtaposed movable contact arms 10m, sb and la, lb. In other words, those portions extending through the juxtapose contact arms of each pin 14s or I have clearances between the same and the associated holes extending through the arms (FIG. 3). This permits the pair of juxtaposed movable contact arms llsa and sb or la, lb to be somewhat movable with respect to each other in the direction of contact pressure. That is, the anchoring pin can be tilted to the axis of the through holes in each arm as shown in FIG. 3 whereby the two movable contacts llsa and sb or la and lb juxtaposed can be always maintained in contact with the opposite stationary contact 6s or I under the contact pressures substantially equal in magnitude to each other even in the case the juxtaposed movable contacts are otherwise somewhat put in different levels.

While the invention has been described in conjunction with the movable contact assembly bridging the stationary contact assembly it is to be understood that the same is equally applicable to movable contact assemblies of circuit interrupters etfecting interruption at a single point.

FIGS. 4 and 5 illustrate another form of the invention applied to a pair of juxtaposed movable contact arms adapted to engage a single staitonary contact arm. A single stationary contact arm 105 is provided at the free end with a stationary contact 106 and a pair of juxtaposed movable contact arms 110a and bare provided at the free ends with the respective movable contacts 111a and b and disposed in substantially parallel relationship with respect to the stationary contact arm 106 in the closed position of the circuit interrupter. The movable contact arms 110a and b are pivotally mounted at the other ends on a support pin 112 fixed to a pair of parallel holder plates 113. An anchoring pin 114 loosely extends through the intermediate portions of the movable contact arms 110a and b and has one tension spring 116 spanned between the same and an anchoring pin 114 fixed to the holder plates 113 on each side of the latter. The pin 114 is adapted to be movable along a guide notch disposed on one side of the holder plates. It is readily understood that the arrangement is operated in a similar manner as previously described in conjunction with FIGS. 1 through 3.

While the invention has been illustrated and described in conjunction with two preferred embodiments thereof,

6 it is to be understood that various changes and modifications may be resorted to without departing from the spirit and scope of the invention.

What is claimed is:

1. In a circuit interrupter of the type interrupting a flow of very excessive current therethrough by the utilization of an electromagnetic repulsion due to the flow of very excessive current, the combination of a stationary contact assembly having attached to one end a stationary contact, a movable contact assembly including a pair of identical movable contact arms disposed in juxtaposed parallel relationship and having attached to one end the respective movable contacts, the stationary and movable contact assemblies being disposed in substantially parallel relationship in the closed position of the interrupter, holder means, a support pin fixed to the holder means to pivotably support the other end portions of the movable contact arms, said movable contact arms having a through hole extending through the intermediate portions thereof, an anchor pin extending through said through hole for a limited tilting movement with respect to the axis of said through hole, tension spring means anchored at one end to the anchoring pin to cooperate with the latter to impart to the pair of movable contacts substantially equal contact pressures under which they are maintained in contact with the stationary contact in the closed position of the interrupter, the movable contact arms being responsive to an electromagnetic repulsion generated between the movable and stationary contact assemblies due to a flow of very excessive current through the interrupter to be rotated away from the stationary contact assembly thereby to interrupt the current, and means for limiting the rotational movement of the movable contact arms.

2. A circuit interrupter as claimed in claim 1 wherein the means for limiting the rotational movement of the movable contact arms is a guide notch disposed on the holder means along which the anchoring pin is moved during the rotational movement of the arms.

3. In a circuit interrupter of the type interrupting a flow of very excessive current therethrough by the utilization of an electromagnetic repulsion due to the flow of very excessive current therethrough, the combination of a stationary contact assembly comprising a pair of bilaterally symmetric, stationary contact arms having attached to one end a pair of stationary contacts, respectively, a movable contact assembly comprising a pair of bilaterally symmetric movable contact units, each including a pair of movable contact arms disposed in juxtaposed parallel relationship and having attached to one end a pair of movable contacts, respectively, the stationary contact arms being disposed in substantially parallel relationship with the movable contact arms in the closed position of the interrupter, holder means, a support pin for each contact -unit fixed to the holder means to pivotably support the other end portions of the movable contact arms of each unit being maintained in rolling contact with those of the contact arms of the other unit, said movable contact arms of each of said units having a through hole extending through the intermediate portions thereof, an anchor pin extending through said through hole for a limited tilting movement with respect to the axis of said through hole, tension spring means spanned between both the anchoring pins to cooperate with each of the anchoring pins to impart to the associated pair of movable contacts substantially equal contact pressure under which they are maintained in contact with the opposite stationary contact in the closed position of the interrupter, the movable contact arms of each unit being responsive to an electromagnetic repulsion generated between the same and the opposite stationary contact arm due to a flow of very excessive current through the interrupter to be rotated away from the opposite stationary contact arm, the rotational movement of the movable contact arms of each unit being opposite in direction to that of the movable contact arms of the other unit, and means for limiting the rotational movements of the movable contact arms of both units.

4. A circuit interrupter as claimed in claim 3 wherein the means for limiting the rotational movement of the movable contact arms is guide notches bilaterally disposed on the holder means along which the anchoring pins are moved during the rotational movement of the arms.

References Cited UNITED STATES PATENTS 3,343,108 9/1967 Murai 335--16 5 HAROLD BROOME, Primary Examiner 

